Tibolone, oral or transdermal hormone replacement and colour Doppler analysis: a prospective, randomised pilot study

Objective: To compare the plasma thromboxane, the plasma viscosity and the Doppler flow modifications induced by tibolone and by oral or transdermal continuous combined hormone replacement therapy. Methods: Forty-two post-menopausal patients underwent either on: oral daily treatment with tibolone (2.5 mg) (Group I; n=14); or continuous oral administration of 0.625 mg conjugated equine estrogens + medroxyprogesterone 5 mg per day (Group II; n=14); or continuous estradiol transdermal supplementation, at a dose of 50 μg per day, + medroxyprogesterone 5 mg per day (Group III; n=14). The duration of the study was 6 months and the patients were submitted to transvaginal ultrasonographic evaluation of pelvic organs; Doppler analysis of the uterine, internal carotid and ophthalmic arteries; thromboxane and plasma viscosity assays in basal condition, and at 1, 3 and 6 months from the beginning of the study. Results: Although the endometrial thickness increased significantly, there were no cases in which it exceeded the normal range (≤5 mm). In all the three groups, the pulsatility index of the uterine, internal carotid and ophthalmic arteries significantly decreased during the therapy showing a reduced impedance since the first month of treatment. Similar variations were observed for the peak systolic blood flow velocity of the internal carotid and ophthalmic arteries. Hormone replacement therapy and tibolone induced a deep, significant and rapid decrease in plasma thromboxane and plasma viscosity levels. Conclusions: Hormone replacement therapy and tibolone seem to have beneficial effects on vascular and hemorrheological parameters.